Secret sharing is a process by which secrets are distributed among an arbitrary number of servers. A concern in secret sharing is the possibility of an adversary who may corrupt a fixed portion of the servers. When the adversary corrupts a server, it learns all information stored on that server. The adversary can force corrupt servers to behave arbitrarily, irrespective of the protocol. Thus, it is imperative to implement a secure secret sharing protocol.
The secret sharing schemes of Herzberg et al. (see the List of Incorporated Cited Literature References, Literature Reference No. 16) and of Cachin et al. (see Literature Reference No. 6) are non-mobile (i.e., they do not allow the set of servers holding the secret to change). Desmedt and Jajodia's scheme (see Literature Reference No. 9) only works for passive adversaries (i.e., it only works if corrupted servers follow the protocol).
The schemes of Wong, Wang, and Wing (see Literature Reference No. 18), of Zhou et al. (see Literature Reference No. 19), and of Schultz (see Literature Reference No. 17) do not have optimal efficiency. The protocols described in Literature Reference Nos. 18 and 19 have communication complexity O(exp(n)), and Literature Reference No. 17 has communication complexity O(n3).
Thus, a continuing need exists for a system having mobile proactive secret sharing (MPSS) functionality that provides perfect security.